Filter screen

Abstract

Provided is a filter screen having a plurality of slots, each slot having a longest principal axis A1 that has a length L, and each slot having a second axis A2 that is perpendicular to A1 and that has a length W, wherein the distance between adjacent slots in the direction of the axes A2 is XP; wherein XP is greater than W; wherein the distance between adjacent slots in the direction of the axes A1 is YP; either wherein L is 800 micrometers or less and XP is 350 micrometers or less, or wherein L is 1600 μm or less and XP is 180 μm or less. Also provided is a method of filtering feed water using such a filter screen.

The invention claimed is: 
     
       1. A filter screen having a plurality of slots, each slot having a longest principal axis A1 that has a length L, and each slot having a second axis A2 that is perpendicular to A1 and that has a length W, wherein the slots are arranged so that
 all the axes A1 are parallel to each other; 
 the slots are disposed in a plurality of rows, wherein the distance between center points of adjacent slots in the direction of the axes A2 is XP; wherein XP is greater than W; 
 the slots are disposed in a plurality of columns, wherein the distance between nearest circumference points of adjacent slots in the direction of the axes A1 is YP; 
 wherein L is 800 micrometers or less, 
 wherein XP is 350 micrometers or less, 
 wherein W is 50 micrometers or less, and 
 wherein the filter has a curved surface. 
 
     
     
       2. The filter screen of  claim 1 , wherein the curved surface is enclosed by top and bottom surfaces. 
     
     
       3. The filter screen of  claim 1 , wherein XP is 200 μm or smaller. 
     
     
       4. The filter screen of  claim 1 , wherein within each row the axes A2 are collinear. 
     
     
       5. The filter screen of  claim 4 , wherein within each column the axes A1 are collinear. 
     
     
       6. The filter screen of  claim 1 , further comprising:
 one or more brushes engaged with the filter screen. 
 
     
     
       7. The filter screen of  claim 1 , wherein the slot has a shape along the Z axis that is substantially uniform. 
     
     
       8. The filter screen of  claim 1 , wherein 90% or more of the slots have W that has a quotient of W/Wav of from 0.8 to 1.2, and wherein Wav is the average width of the slots in that screen.